In general, an oil pump including an inner rotor, an outer rotor, and a plurality of vanes that connects the inner rotor and the outer rotor is known. Such an oil pump is disclosed in Japanese Patent Laying-Open No. 2012-255439, for example.
In Japanese Patent Laying-Open No. 2012-255439, there is disclosed a pendulum-slider pump (oil pump) including an inner rotor rotationally driven, an enter rotor rotated outside the inner rotor, and a plurality of pendulums (vanes) chat connects the outer periphery of the inner rotor and the inner periphery of the outer rotor. In this pendulum-slider pump described in Japanese Patent Laying-Open No. 2012-255439, tip ends of the pendulums are hinged to the outer periphery of the inner rotor, and base parts thereof are fitted into recess parts of the outer rotor formed, to correspond to the respective pendulums. In response to relative eccentricity between the inner rotor and the outer rotor, each of the pendulums is rotationally moved while swinging about, a connecting part with the inner rotor along with the rotation of the inner rotor, and the base parts of the pendulums are displaced to freely appear from and disappear into the recess parts of the outer rotor. At this time, a plurality of volume chambers individually partitioned by the pendulums is sequentially deformed along with the rotation of the inner rotor, thereby providing a pulping function.
Furthermore, in order to cause the pendulums to swing, intermediate parts of the respective pendulums that connect one ends and the other ends are narrower than both ends (the tip ends and the base parts). Thus, the intermediate parts that enter the recess parts of the outer rotor are prevented from contacting with inner walls of the recess parts due to swinging of the pendulums. In addition, each of the pendulum swings, whereby both the inner rotor and the outer rotor having relative eccentricity smoothly rotate.